Renal phosphoenolpyruvate carboxykinase turnover in hypo- and hyperthyroid rat in vivo.
The effect of hypo- and hyperthyroidism on activity, synthesis and degradation of renal cytosolic phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) was studied in the rat by radioimmunological techniques. In hypo- and euthyroid rats, starvation induced similar alterations in enzyme activities and relative rates of synthesis, whereas in hyperthyroid rats the increase in both was significantly reduced. Substitution of L-thyroxine in hypothyroid rats resulted in a decrease in activity and synthesis within 18 h as observed in hyperthyroid animals. The apparent half-life of the enzyme measured by double-pulse labeling experiments was approx. 13 h in euthyroid animals. The rate of degradation was unaffected by the different thyroid states.
D000818:Animals; D002245:Carbon Dioxide; D003600:Cytosol / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D006980:Hyperthyroidism / Q000201:enzymology*; D007037:Hypothyroidism / Q000201:enzymology*; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation; D013974:Thyroxine / Q000494:pharmacology
D002245:Carbon Dioxide; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D013974:Thyroxine